I make it 10x2 and 6x4. Add in 4x3, gives scope for:
16x3
4x2
This would allow 2x 10 car formations for the peaks, although at the risk of requiring all the 2 car units to be in traffic.
Perhaps we're more likely to see the 3 car units reformed into 4 cars to give
8x4
12x2
This would allow more 10 car trains to be formed up, and might allow at least some of the Ashford-Brighton trains to be made up of either 1x4 or 2x2, although without working out potential diagrams this could be asking too much. It might work is Ashford-Brighton was cut back to Ashford-Eastbourne however.
The other possibility is the Scotrail ones stay as they are and work Ashford-Brighton, allowing the 2-car units to be added to Uckfield diagrams.
Whichever way it ends up, it's all a bit messy as there's a lot of space being wasted with too many driving cabs and more toilets than required. They would be better with just 3-car and 4-car units, but they would need quite a few more centre cars to make all the 2-cars up to 3.